One or more screenings or screens have been used in shaker or vibrating screen apparatus to size material passing through the screens. Known screens/screenings typically consist of a plurality of warp screening elements and a plurality of retaining members operably associated with the warp screening elements to form an integral screen segment having a plurality of openings for permitting suitably sized material to pass through the screen. The warp screening elements can be wires or plastic members. The openings can be square, rectangular or diamond shaped. Alternatively, the screen can be formed as a long slot screen where the warp screening elements are maintained in spaced parallel relation by retaining members arranged in groups of three at spaced intervals along the length of the warp screening elements. The retaining members can be weft wires.
Screen design is problematic as numerous factors can adversely impact the performance and longevity of the screen. For example, the through put of the screen is extremely important as a screen which does not allow for efficient sizing or grading of material will not meet commercial demands although the screen can satisfactorily classify material. Another significant factor is the ability of the screen to maintain the desired opening size to ensure that material passing through the screen can be accurately classified. A further significant factor is the ability of the screen to avoid blinding. Specifically, where one or more openings in the screen become partially or completely obstructed by material or foreign matter, the performance of the screen greatly deteriorates. Moreover, the longevity of the screen is an important factor to the commercial success of the screen.
Conventional screens have been unable to address one or more of the aforementioned factors to the detriment of the screen and it commercial success.